This invention relates to certain novel piperidine derivatives and to their use as stabilizers for polymers, particularly synthetic polymers, and provides processes for their preparation. More specifically, it is concerned with compounds having two or three piperidine residues.
Certain classes of piperidine derivatives are known to be useful stabilizers for synthetic polymers. Amongst the known classes of piperidine derivatives are: 4-unsubstituted piperidine derivatives (Japanese Patent Publication No. 46-31733, U.S. Pat. No. 3,975,357 and German Offenlegungsschrift No. 2,621,841); 4-acyloxypiperidine derivatives (U.S. Pat. No. 3,640,928, No. 3,705,166, No. 3,840,494, No. 3,940,363 and No. 3,992,390, British Patent Specifications No. 1,399,239 and No. 1,399,240 and German Offenlegungsschrift No. 2,623,422) 4-ketalpiperidine derivatives (U.S. Patent Specification No. 3,790,525, No. 3,859,293, No. 3,899,464 and No. 3,940,363, British Pat. Specification No. 1,417,835, Japanese Patent Application No. 49-77944, as laid open to public inspection, and German Offenlegungsschrift No. 2,621,855); 4-aminopiperidine derivatives (U.S. Patent Specification No. 3,705,166, No. 3,839,273 and No. 3,904,581, Japanese Patent Application No. 49-60337, as laid open to public inspection, and German Offenlegungsschrift No. 2,621,870); and 1,3,8-triazaspiro[4.5]decane-2,4-dione derivatives (U.S. Patent Specifications No. 3,542,729, No. 3,705,126, No. 3,941,744 and No. 3,975,462, Japanese Patent Application No. 49-72332, as laid open to public inspection and German Offenlegungsschrift No. 2,623,464).
However, these known stabilizers have a number of disadvantages. For example, some of them, in spite of being good light stabilizers, are relatively volatile and are therefore of no practical use in the stabilization of synthetic polymers, since they volatilize at processing temperatures and may also volatilize during prolonged storage of the stabilized articles. Others of these compounds can easily be extracted from synthetic polymers with water or with organic solvents and, again, are of little practical use for the stabilization of synthetic polymers. Some known piperidine derivatives have a single piperidine residue in the molecule and, prior to the present invention, stabilizing compounds containing two or three piperidine residues linked through their 1-positions by a suitable bridging group, e.g. by means of a group derived from 2,2-bis[4-(2-hydroxpropyl)phenyl]propane, which are structurally quite different from the known piperidine derivatives, have not hitherto been discovered.